Humidostat



y 1934- M. E. HENNING 1,956,795

HUMIDOSTAT Filed Jan. 23, 1933 Patented May 1, 1934- HUMIDOSTAT MalcolmE. Henning, Des Moines, Iowa, assignor to Penn Electric Switch 00., DesMoines, Iowa,

a corporation of Iowa Application January 23, 1933, Serial No. 653,09412 Claims. (01. 297-1) An object of my present invention is to provide ahygroscopic control switch of simplified construction having an easilyand inexpensively manufactured humidity responsive control 6 member.

A further object is to provide a humidity responsive control memberwhich is rugged in construction, yet very sensitive to humidity changes,the elements of the member being so formed and associated that there isan entire elimination of stresses and strains present in the usual typeof humidity responsive member.

More particularly, it is my object to provide a humidity responsivemember consisting of a cor rugated resilient element and an elementmounted alongside thereof with the ends of the elements securedtogether, the second mentioned element being responsive to humidityconditions for im parting swinging movement to both elements and thusproviding a control member which can be utilized for opening and closingswitch contacts or performing other controlling operations.

Still a. further object is to arrange the control member in the form ofa spiral so that considerable length without utilizing prohibitive spacecan be secured.

Another object is to provide means for adjusting the range of thehumidity responsive member.

With these and other objects in view my invention consists in theconstruction, arrangement and combination of the various parts of mydevice, whereby the objects contemplated are attained, as hereinaftermore fully set forth,

pointed out in my claims, and illustrated in the accompanying drawing,in which:

Figure 1 is a front elevation of a hygroscopic control switch embodyingmy invention showing the cover therefor removed.

Figure 2 is a side elevation of the same showing the cover in section.

Figure 3, is a diagrammatic view of the hygroscopic control membershowing it in the dry position.

Figure 4 is a similar diagrammatic view showing it in the humidposition.

Figure 5 is a diagrammatic view showing a hygroscopic control'memberwhich is not of spiral formation and illustrates the action of themember under exceptionally dry atmospheric conditions.

Figure 6 is a similar diagrammatic view showing different dimensionsused for the parts and illustrating an exceptionally humid atmospheric Icondition; and 1 Figure '1. is an enlarged view of a connection used'inthe structure.

On the accompanying drawing, I have used the reference numeral 10 toindicate a base. The base 10 is provided with openings 12 and 14 throughwhich screws may extend for securing the base to a wall or othersurface.

A post 16 extends from the base 10 and has pivoted thereon, an arm 18.The arm 18 is adjustable by means 0 an arm 20 pivoted at 22 and having apair of spaced sides 24 engaging an eccentric 26 mounted on the arm 18.The eccentric 26 is secured to the arm 18 by a screw 28 which canbe'loosened whereupon the eccentric can be rotated by a screw driverthrust into a slot 30. This provides a factory adjustment for the arm 18relative to the arm 20.

The arm 20 has an operating knob 32 which extends through a slot 34 of agrid-like casing member 36. The casing member 36 is held in position onthe base 10 by spring catches 38.

I provide a hygroscopic control member A. It comprises a corrugatedelement 40 of resilient material, such as sheet metal, a humidityresponsive element 42 which will expand or swell upon an increase ofhumidity in the surrounding atmosphere and a switch arm 44. 4

The element 42 may be made of paper or the like.

The element 42 has its ends secured by screws 46 and 48 to the arm 18and to the switch arm 44, respectively. The switch arm includes aconnecting member 440. of insulating material to prevent a short circuitbetween the switch arm 44 and the corrugated element 40.

It is desirable that the screws 46 and 48 make good connection with theends of the paper element 42. I therefore provide metal clips 50 (seeFigure '7) which are of triple thickness folded construction with theends of the paper element 42 folded in them. Their shape is simplifiedin Figure 1 because the figure is on too small a scale to illustratethem in full detail.

The screw 46 anchors both one end of the element 42 and one end of theelement 40 to the arm 18, which serves as an adjustable anchorage forthe control member A. The screw 48 is provided for some longitudinaladjustment of the outer end of the paper element 42 relative to thecorrugated element 40, such adiustment being effected at the factory. Itwill be remembered that the eccentric 26 is also a factory adjustmentand after the screw 48and the eccentric 26 are adjusted, the adjustmentby the user can be effected by moving the knob 32 so as to adjust thehygroscopic control switch for desired operation, for instance slightlyabove or slightly below a forty-five per cent humidity condition.

The switch arm 44 carries a movable contact 52 adapted to coact with anintermediate spring mounted contact 54, which in turn coacts with astationary contact 56 for establishing an electric circuit.

The circuit may extend through a humidifying device or the like forincreasing the humidity content of the atmosphere when the switchcontacts are engaged. A permanent magnet 58 is provided to aflect anarmature piece 60 mounted on the switch arm 44. for providing snapaction when the switch contacts are separated.

In Figures 5 and 6, I have shown how the elemutants 46 and 42 can besomewhat simplified. In these figures, they are arranged in a straightline rather than spirally. The action of the control member is bestillustrated in these figures.

In Figure 5, the action of the corrugated memher so because of excessivedryness in the atmosphere is illustrated by dotted lines. The contacts52 and 56 have been engaged because of the contraction of the paperelement 42, but thereafter a continued dry condition of the air hascaused further contraction. Such further contraction, instead of placingthe paper element 42 under greatly increased strain, merely causes thecorrugations to be contracted, for instance to the dotted line position(which is greatly exaggerated). Thus an overrun in the dry direction iseffectively taken care of.

In Figure 6, an overrun in the humid direction is illustrated. A stop isshown diagrammatically at 61, which in the case of the device shown inFigures 1 and 2, would be the casing 36. An increase in humidity afterthe control member strikes the stop would tend to lengthen the paperelement 42, for instance, to the dotted line position and it couldmerely buckle away from the corrugated element 40 without placing anyundesired strain on the parts.

The sensitivity of the hygroscopic control memer may be predetermined bythe thickness of the material in the element 40 and the depth of thecorrugations. For instance, in Figure 5, thin material and deepcorrugations are illustrated which would provide a much more sensitivecontrol device than the one shown in Figure 6 wherein the material isthicker and the corrugations are shallower. The diii'erence in Figures 5and 6 illustrates how various adaptations of the invention can be workedout, the element in Figure 6 being considerably more powerful than theone in Figure 5. Thus the construction can be varied to make theinvention applicable to different installations.

in Figured, I have shown by dotted lines how the paper element 42 canbuckle away from the corrugated element 40 when the parts of a spirallyarranged hygroscopic control member are inthe position illustrated byFigure 6.

My hygroscopic member is so constructed as to prevent strains caused byover and under runs which would be encountered in members composed ofelements cemented or otherwise secured together.

A further advantage resides in the spaces between the apices of thecorrugations of the element 40 providing extra. surface for contact ofthe atmosphere with the humidity responsive element 42.

Changes as already suggested and others may be made without departingfrom the real spirit and purpose of my invention, and it is my intentionto cover by my claims, any modified forms of structure or use ofmechanical equivalents, which may be reasonably included within theirscope.

I claim as my invention:

1. Ida hygroscopic controi device, a control member comprising acorrugated metal element and a humidity responsive element arranged sideby side, the ends of said humidity responsive element being secured tothe ends of said corrugated metal eIement, one end of said controlmember being anchored whereby the other end thereof moves laterallydependent upon humidity conditions of the surrounding atmosphere.

2. In a hygroscopic control device, a control member comprising acorrugated resilient element and a humidity responsive element arrangedside by side, the ends ot'said humidity responsive element being securedto the ends or said corrugated resilient element, one end of saidcontrol member being anchored whereby the other end thereof moveslaterally dependent upon humidity conditions of the surroundingatmosphere.

3. In a hygroscopic control device, a control member comprising acorrugated resilient element and a humidity responsive element arrangedside by side, the ends of said humidity responsive element being securedto the ends of said corrugated resilient element and anchorage means,one end of said control member being secured thereto whereby the otherend of said member will move laterally depending upon the moisturecontent of the surrounding atmosphere.

4. In a hygroscopic control device, a control member comprising a.corrugated resilient element and a humidity responsive element arrangedside by side, the ends of said humidity responsive element being securedto the ends of said corrugated resilient element, anchorage means, oneend of said control member being secured thereto whereby the other endof said memher will move laterally depending upon the moisture contentoi. the surrounding atmosphere and adjustable means for changing theposition of said anchorage means and thereby the position 01' said otherend of said control member and the setting of said control device.

5. In a hygroscopic control device, a control member comprising acorrugated element and a humidity responsive element arranged side byside, the ends of said humidity responsive element being secured to theends of said corrugated element but being otherwise free therefrom, oneend 130.

or said control member being anchored whereby the other end thereofmoves laterally dependent upon humidity conditions of the surroundingatmosphere.

6. A'humidity sensitive element comprising a 35 curved spring, a thinflexible hygroscopic strip and means for supporting said strip thereonin spaced relation to spaced portions of the convex face of said curvedspring, said means providing aeration for the inner surface of saidhygro- 14 scopic strip, the ends of said strip being secured to the endsof said curved spring, one end of said humidity sensitive element beinganchored and the other end providing'lateral movement with a change ofhumidity of the surrounding atmosphere.

7. An elongated humidity sensitive element comprising a curved spring, ahygroscopic strip and means for supporting said strip in spaced relationto spaced portions of the convex face of up said curved spring, the endsof said hygroscopic strip being secured to the ends of said curvedspring, one end of said humidity sensitive element being anchored, theother end thereof providing lateral movement with a change of humidityof the surrounding atmosphere, said curved spring being longitudinallyflexible to limit the stress in said hygroscopic strip at low humidity.

8. An elongated humidity sensitive element comprising a flexible stripin curved form, formations on said strip and a hygroscopic strip held inspaced relation to spaced portions of the outer face of said flexiblestrip by said formations, the ends of said hygroscopic strip beingsecured to the ends of said flexible strip, one end of said humiditysensitive element being anchored, the other end thereof providinglateral movement with a change of humidity of the surroundingatmosphere, said flexible strip having limited longitudinal expansionfor relieving the stress in said hygroscopic strip at high humidities.

9. In a humidity sensitive element, a curved spring having spacedprojections on the convex side thereof and a thin flexible hygroscopicstrip having its ends only anchored tothe ends of said curved spring andlying along said projections,-

one end of said element being anchored whereby the other end moveslaterally in response to humidity changes of the surrounding atmosphere.

10. In a humidity sensitive element, a spirally arranged spring havingspaced projections on the convex side thereof and a thin flexiblehygroscopic strip having its ends anchored to said spring and lyingalong said projections, the space between said projections providing airspaces for aeration of the hygroscopic strip, one end of said elementbeing anchored whereby the other end thereof moves laterally in responseto humidity changes of the surrounding atmosphere.

11. In a humidity sensitive element, a curved flexible element havingspaced projections on the convex side thereof and a thin flexiblehygroscopic strip anchored to said curved flexible element and lyingalong and tangent to the outer end of each of said projections, one endof said humidity sensitive element being anchored whereby the other endmoves laterally in response to humidity changes of the surroundingatmosphere.

.12. A humidity sensitive element comprising a curved spring withintegral projections on its convex surface and a strip of thin flexiblehygroscopic material supported on the outer ends of said integralprojections, the ends of said hygroscopic strip being secured to theends only of said curved spring and thereby normally held in contacttherewith, one end of said humidity sensitive element being anchored andthe other end thereby providing lateral movement with a change ofhumidity of the surrounding atmosphere.

MALCOLM E. HENNING.

